1. Field of the Invention
The present invention relates generally to wood and coal heating units and more particularly concerns heating units, their means and method of combustion. A base burner with preheated and indirect primary draft in the primary combustion zone. Further comprising a secondary combustion chamber and means for completing combustion of the unburned volatile gases leaving the primary combustion zone.
2. Description of Prior Art
The prior art of wood and coal fired heating units (many called air-tights) their method and means of combustion are unable to prevent the condensation of pyroligneous acid or creosote formation in the exhausting flue. Various designs of prior art have been created to try and overcome the creosote problem and obtain more complete combustion. Several designs of prior art are the downdraft, base burners with secondary combustion chamber, preheating the draft and magnetic snap action draft control. But in practice with their unbalanced design the desired results were not achieved. The obvious solution in the downdraft system was to reverse the direction of the draft so that the volatile gases were carried downward and burned in the heat of the coals. The operation of this design was difficult and unpleasant backpuffing occurred unless the chimney was hot and drawing well. Several systems on the design of the base burner and secondary combustion chamber have attempted to obtain more complete combustion and overcome the creosote problem. These systems using direct primary draft and inadequately heated secondary combustion chamber, are also notorious producers of creosote formation. Another attempt was made to overcome the creosote problem, using the same mentioned system in combination with the use of a magnetic snap action draft control, but the desired results were not acheived.
The prior art of preheating of the primary draft was desireable, but these systems also incorporated a direct primary draft through the charge of fuel. Such systems with no or improperly designed secondary combustion chamber, are also notorious producers of creosote formation. Several designs of prior art, using secondary combustion chambers have them built where the greatest portion is on the outside of the heater magazine. At times such arrangement is also unsatisfactory, because of the fact that the secondary combustion chamber operates under a too low temperature or under the ignition point of the volatile gases, especially at a time when the temperature should be at its highest, therefor my invention houses the secondary combustion chamber all inside of the heater the body, with a flattended design, in such a way that a greater portion is in proximity of the primary combustion zone, resulting the secondary combustion to operate at a much higher temperature and at a longer length of time in the combustion cycle, resulting in more complete combustion of the volatile gases.
It has been accepted practice in combustion processes to supply the primary draft direct through the charge of fuel. At times in such an arrangement, the rate of combustion is difficult to regulate and can only be regulated with closing down of the primary draft, resulting a system duplicating wood tar distillation. With such systems being "air tight" there is a stage in combustion, where it is unusually difficult to keep the primary volatile gases in balance with the capacity of the secondary combustion cycle, especially with units being air-tight. Our design (with draft in closed position) will permit a small amount of air into the unit, encourging more of a balanced combustion and less creosote formation, however the unit being sufficiently air tight to have full control of combustion. It is to be noted that this is much easier accomplished, with our use of indirect primary draft.
It should be understood that deposition of the unburned gases as creosote formation comes mostly when wood is used as fuel. The creosote deposits in flues or chimney can become a nuisance and creosote an inflameable substance can become very dangerious, esecially if the creosote ignites. What is needed then is a heating unit comprising a method and means to adequately burn off the volatile gases considerably retarding the creosote problem to its maximum. A unit easy to control and capable of a very even heat output, plus the utmost in safety. The present invention simultaneously achieves all of these results.